Improve CHAT API and repository support.

Change CHAT API call GET /chat/search to better support the two
main scenarios of:

group-based chatting: supply txGroupId only
private chatting: supply 2 'involving' addresses only

Added some DB indexes to cater for above.

GET /chat/search now returns specialized ChatMessage objects
instead of ChatTransactions. This is to reduce unnecessary fetching
of data from repository, and onward sending to API client.

src/main/java/org/qortal/api/resource/ChatResource.java

@@ -24,6 +24,7 @@ import org.qortal.api.ApiErrors;
 import org.qortal.api.ApiExceptionFactory;
 import org.qortal.api.Security;
 import org.qortal.crypto.Crypto;
+import org.qortal.data.chat.ChatMessage;
 import org.qortal.data.transaction.ChatTransactionData;
 import org.qortal.data.transaction.TransactionData;
 import org.qortal.repository.DataException;
@@ -51,14 +52,14 @@ public class ChatResource {
 	@Path("/search")
 	@Operation(
 		summary = "Find chat messages",
-		description = "Returns CHAT transactions that match criteria.",
+		description = "Returns CHAT messages that match criteria. Must provide EITHER 'txGroupId' OR two 'involving' addresses.",
 		responses = {
 			@ApiResponse(
-				description = "transactions",
+				description = "CHAT messages",
 				content = @Content(
 					array = @ArraySchema(
 						schema = @Schema(
-							implementation = ChatTransactionData.class
+							implementation = ChatMessage.class
 						)
 					)
 				)
@@ -66,18 +67,19 @@ public class ChatResource {
 		}
 	)
 	@ApiErrors({ApiError.INVALID_CRITERIA, ApiError.INVALID_ADDRESS, ApiError.REPOSITORY_ISSUE})
-	public List<ChatTransactionData> searchChat(@QueryParam("before") Long before, @QueryParam("after") Long after,
+	public List<ChatMessage> searchChat(@QueryParam("before") Long before, @QueryParam("after") Long after,
 			@QueryParam("txGroupId") Integer txGroupId,
-			@QueryParam("sender") String senderAddress,
-			@QueryParam("recipient") String recipientAddress,
+			@QueryParam("involving") List<String> involvingAddresses,
 			@Parameter(ref = "limit") @QueryParam("limit") Integer limit,
 			@Parameter(ref = "offset") @QueryParam("offset") Integer offset,
 			@Parameter(ref = "reverse") @QueryParam("reverse") Boolean reverse) {
-		// Check any provided addresses are valid
-		if (senderAddress != null && !Crypto.isValidAddress(senderAddress))
-			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
+		// Check args meet expectations
+		if ((txGroupId == null && involvingAddresses.size() != 2)
+				|| (txGroupId != null && !involvingAddresses.isEmpty()))
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
-		if (recipientAddress != null && !Crypto.isValidAddress(recipientAddress))
+		// Check any provided addresses are valid
+		if (involvingAddresses.stream().anyMatch(address -> !Crypto.isValidAddress(address)))
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_ADDRESS);
 
 		if (before != null && before < 1500000000000L)
@@ -87,12 +89,11 @@ public class ChatResource {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			return repository.getChatRepository().getTransactionsMatchingCriteria(
+			return repository.getChatRepository().getMessagesMatchingCriteria(
 					before,
 					after,
 					txGroupId,
-					senderAddress,
-					recipientAddress,
+					involvingAddresses,
 					limit, offset, reverse);
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);

src/main/java/org/qortal/data/chat/ChatMessage.java

@@ -0,0 +1,95 @@
+package org.qortal.data.chat;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class ChatMessage {
+
+	// Properties
+
+	private long timestamp;
+
+	private int txGroupId;
+
+	private byte[] senderPublicKey;
+
+	/* Address of sender */
+	private String sender;
+
+	/* Registered name of sender (if any) */
+	private String senderName; // can be null
+
+	/* Address of recipient (if any) */
+	private String recipient; // can be null
+
+	/* Registered name of recipient (if any) */
+	private String recipientName; // can be null
+
+	private byte[] data;
+
+	private boolean isText;
+	private boolean isEncrypted;
+
+	// Constructors
+
+	protected ChatMessage() {
+		/* For JAXB */
+	}
+
+	// For repository use
+	public ChatMessage(long timestamp, int txGroupId, byte[] senderPublicKey, String sender, String senderName,
+			String recipient, String recipientName, byte[] data, boolean isText, boolean isEncrypted) {
+		this.timestamp = timestamp;
+		this.txGroupId = txGroupId;
+		this.senderPublicKey = senderPublicKey;
+		this.sender = sender;
+		this.senderName = senderName;
+		this.recipient = recipient;
+		this.recipientName = recipientName;
+		this.data = data;
+		this.isText = isText;
+		this.isEncrypted = isEncrypted;
+	}
+
+	public long getTimestamp() {
+		return this.timestamp;
+	}
+
+	public int getTxGroupId() {
+		return this.txGroupId;
+	}
+
+	public byte[] getSenderPublicKey() {
+		return this.senderPublicKey;
+	}
+
+	public String getSender() {
+		return this.sender;
+	}
+
+	public String getSenderName() {
+		return this.senderName;
+	}
+
+	public String getRecipient() {
+		return this.recipient;
+	}
+
+	public String getRecipientName() {
+		return this.recipientName;
+	}
+
+	public byte[] getData() {
+		return this.data;
+	}
+
+	public boolean isText() {
+		return this.isText;
+	}
+
+	public boolean isEncrypted() {
+		return this.isEncrypted;
+	}
+
+}

src/main/java/org/qortal/repository/ChatRepository.java

@@ -2,16 +2,17 @@ package org.qortal.repository;
 
 import java.util.List;
 
-import org.qortal.data.transaction.ChatTransactionData;
+import org.qortal.data.chat.ChatMessage;
 
 public interface ChatRepository {
 
-	public List<ChatTransactionData> getTransactionsMatchingCriteria(
-			Long before,
-			Long after,
-			Integer txGroupId,
-			String senderAddress,
-			String recipientAddress,
+	/**
+	 * Returns CHAT messages matching criteria.
+	 * <p>
+	 * Expects EITHER non-null txGroupID OR non-null sender and recipient addresses.
+	 */
+	public List<ChatMessage> getMessagesMatchingCriteria(Long before, Long after,
+			Integer txGroupId, List<String> involving,
 			Integer limit, Integer offset, Boolean reverse) throws DataException;
 
 }

src/main/java/org/qortal/repository/hsqldb/HSQLDBChatRepository.java

@@ -5,10 +5,9 @@ import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.List;
 
-import org.qortal.data.transaction.ChatTransactionData;
+import org.qortal.data.chat.ChatMessage;
 import org.qortal.repository.ChatRepository;
 import org.qortal.repository.DataException;
-import org.qortal.transaction.Transaction.TransactionType;
 
 public class HSQLDBChatRepository implements ChatRepository {
 
@@ -19,58 +18,48 @@ public class HSQLDBChatRepository implements ChatRepository {
 	}
 
 	@Override
-	public List<ChatTransactionData> getTransactionsMatchingCriteria(Long before, Long after, Integer txGroupId,
-			String senderAddress, String recipientAddress, Integer limit, Integer offset, Boolean reverse)
+	public List<ChatMessage> getMessagesMatchingCriteria(Long before, Long after, Integer txGroupId,
+			List<String> involving, Integer limit, Integer offset, Boolean reverse)
 			throws DataException {
-		boolean hasSenderAddress = senderAddress != null && !senderAddress.isEmpty();
-		boolean hasRecipientAddress = recipientAddress != null && !recipientAddress.isEmpty();
+		// Check args meet expectations
+		if ((txGroupId != null && involving != null && !involving.isEmpty())
+				|| (txGroupId == null && (involving == null || involving.size() != 2)))
+			throw new DataException("Invalid criteria for fetching chat messages from repository");
+
+		StringBuilder sql = new StringBuilder(1024);
+
+		sql.append("SELECT created_when, tx_group_id, creator, sender, SenderNames.name, "
+				+ "recipient, RecipientNames.name, data, is_text, is_encrypted "
+				+ "FROM ChatTransactions "
+				+ "JOIN Transactions USING (signature) "
+				+ "LEFT OUTER JOIN Names AS SenderNames ON SenderNames.owner = sender "
+				+ "LEFT OUTER JOIN Names AS RecipientNames ON RecipientNames.owner = recipient ");
+
+		// WHERE clauses
 
-		String signatureColumn = "Transactions.signature";
 		List<String> whereClauses = new ArrayList<>();
 		List<Object> bindParams = new ArrayList<>();
 
-		// Tables, starting with Transactions
-		StringBuilder tables = new StringBuilder(256);
-		tables.append("Transactions");
-
-		if (hasSenderAddress || hasRecipientAddress)
-			tables.append(" JOIN ChatTransactions USING (signature)");
-
-		// WHERE clauses next
-
-		// CHAT transaction type
-		whereClauses.add("Transactions.type = " + TransactionType.CHAT.value);
-
 		// Timestamp range
 		if (before != null) {
-			whereClauses.add("Transactions.created_when < ?");
+			whereClauses.add("created_when < ?");
 			bindParams.add(before);
 		}
 
 		if (after != null) {
-			whereClauses.add("Transactions.created_when > ?");
+			whereClauses.add("created_when > ?");
 			bindParams.add(after);
 		}
 
-		if (txGroupId != null)
-			whereClauses.add("Transactions.tx_group_id = " + txGroupId);
-
-		if (hasSenderAddress) {
-			whereClauses.add("ChatTransactions.sender = ?");
-			bindParams.add(senderAddress);
+		if (txGroupId != null) {
+			whereClauses.add("tx_group_id = " + txGroupId); // int safe to use literally
+			whereClauses.add("recipient IS NULL");
+		} else {
+			whereClauses.add("((sender = ? AND recipient = ?) OR (recipient = ? AND sender = ?))");
+			bindParams.addAll(involving);
+			bindParams.addAll(involving);
 		}
 
-		if (hasRecipientAddress) {
-			whereClauses.add("ChatTransactions.recipient = ?");
-			bindParams.add(recipientAddress);
-		}
-
-		StringBuilder sql = new StringBuilder(1024);
-		sql.append("SELECT ");
-		sql.append(signatureColumn);
-		sql.append(" FROM ");
-		sql.append(tables);
-
 		if (!whereClauses.isEmpty()) {
 			sql.append(" WHERE ");
 
@@ -88,19 +77,31 @@ public class HSQLDBChatRepository implements ChatRepository {
 
 		HSQLDBRepository.limitOffsetSql(sql, limit, offset);
 
-		List<ChatTransactionData> chatTransactionsData = new ArrayList<>();
+		List<ChatMessage> chatMessages = new ArrayList<>();
 
 		try (ResultSet resultSet = this.repository.checkedExecute(sql.toString(), bindParams.toArray())) {
 			if (resultSet == null)
-				return chatTransactionsData;
+				return chatMessages;
 
 			do {
-				byte[] signature = resultSet.getBytes(1);
+				long timestamp = resultSet.getLong(1);
+				int groupId = resultSet.getInt(2);
+				byte[] senderPublicKey = resultSet.getBytes(3);
+				String sender = resultSet.getString(4);
+				String senderName = resultSet.getString(5);
+				String recipient = resultSet.getString(6);
+				String recipientName = resultSet.getString(7);
+				byte[] data = resultSet.getBytes(8);
+				boolean isText = resultSet.getBoolean(9);
+				boolean isEncrypted = resultSet.getBoolean(10);
 
-				chatTransactionsData.add((ChatTransactionData) this.repository.getTransactionRepository().fromSignature(signature));
+				ChatMessage chatMessage = new ChatMessage(timestamp, groupId, senderPublicKey, sender,
+						senderName, recipient, recipientName, data, isText, isEncrypted);
+
+				chatMessages.add(chatMessage);
 			} while (resultSet.next());
 
-			return chatTransactionsData;
+			return chatMessages;
 		} catch (SQLException e) {
 			throw new DataException("Unable to fetch matching chat transactions from repository", e);
 		}

src/main/java/org/qortal/repository/hsqldb/HSQLDBDatabaseUpdates.java

@@ -598,6 +598,10 @@ public class HSQLDBDatabaseUpdates {
 					// Chat transactions
 					stmt.execute("CREATE TABLE ChatTransactions (signature Signature, sender QortalAddress NOT NULL, nonce INT NOT NULL, recipient QortalAddress, "
 							+ "is_text BOOLEAN NOT NULL, is_encrypted BOOLEAN NOT NULL, data MessageData NOT NULL, " + TRANSACTION_KEYS + ")");
+					// For finding chat messages by sender
+					stmt.execute("CREATE INDEX ChatTransactionsSenderIndex ON ChatTransactions (sender)");
+					// For finding chat messages by recipient
+					stmt.execute("CREATE INDEX ChatTransactionsRecipientIndex ON ChatTransactions (recipient, sender)");
 					break;
 
 				default: